Child Domestic Work, Violence, and Health Outcomes: A Rapid Systematic Review

This rapid systematic review describes violence and health outcomes among child domestic workers (CDWs) taken from 17 studies conducted in low- and middle-income countries. Our analysis estimated the median reported rates of violence in CDWs aged 5–17-year-olds to be 56.2% (emotional; range: 13–92%), 18.9% (physical; range: 1.7–71.4%), and 2.2% (sexual; range: 0–62%). Both boys and girls reported emotional abuse and sexual violence with emotional abuse being the most common. In Ethiopia and India, violence was associated with severe physical injuries and sexual insecurity among a third to half of CDWs. CDWs in India and Togo reported lower levels of psycho-social well-being than controls. In India, physical punishment was correlated with poor psycho-social well-being of CDWs [OR: 3.6; 95% CI: 3.2–4; p < 0.0001]. Across the studies, between 7% and 68% of CDWs reported work-related illness and injuries, and one third to half had received no medical treatment. On average, children worked between 9 and 15 h per day with no rest days. Findings highlight that many CDWs are exposed to abuse and other health hazards but that conditions vary substantially by context. Because of the often-hidden nature of child domestic work, future initiatives will need to be specifically designed to reach children in private households. Young workers will also benefit from strategies to change social norms around the value and vulnerability of children in domestic work and the long-term implications of harm during childhood.


Introduction
Evidence from around the world indicates that exposure to adverse childhood experiences (ACE) hinders children's development and wellbeing and can often have lifelong effects [1,2]. Adverse childhood experiences (ACE) are associated with a range of illnesses (e.g., heart disease, lung cancer, sexually transmitted infections), mental health symptoms (e.g., depression, anxiety), and social problems (relationship problems, poor job performance, revictimization or perpetrators) in adulthood [1,2]. Children engaged in child labor, including child domestic workers, are particularly vulnerable to different forms of violence, exploitation, and neglect [3].
Child domestic workers are defined as children younger than 18 years who are engaged in domestic work outside the home of their own family for remuneration (whether paid or unpaid), a portion of whom work in hazardous or exploitative situations akin to slavery [4]. Global estimates suggest that that approximately 17.2 million children work as domestic workers, of whom over half (11.2 million) are aged between 5 to 14 years and 67% are girls [5,6]. There remains very limited data on regional estimates of child domestic workers; however, statistics indicate that Asia contains the most (41%) domestic workers [7] and the second-most (60.7 million) child laborers in the world [8]. In many contexts, domestic work is perceived to be safe and beneficial for children who take jobs in employing households to escape poverty, often as a better option than more hazardous income opportunities or to improve their life prospects [9]. Child domestic work is rarely acknowledged as 'employment' since, for many employing households, child domestic workers are often 'relatives' or 'fostered' children, even though they may be treated differently to other family members [10,11]. Hidden behind closed doors in private households, child domestic workers are often denied the protection of national labor laws and legislation [12].
Household responsibilities for child domestic workers often include cleaning, cooking, and caring tasks, and are similar to those of other domestic workers [4]. Such tasks may be considered harmless but can have adverse consequences for children, particularly when they lack the training, experience, and physical and mental capacities to carry out tasks that are not age appropriate. For instance, many domestic tasks can be hazardous for child domestic workers, such as using sharp kitchen utensils, working in monotonous tasks in an awkward position for long hours, assisting with maintenance work from dangerous heights, caring for sick persons, and handling chemicals [4]. Having unspecified or fluid working hours may mean that child domestic workers have to remain available 24 h per day, seven days per week, which can cause sleep deprivation and exhaustion. Chronic fatigue, especially among adolescents, can lead to accidents and cause headaches, and stress-or depression-related syndromes [13]. It is also not uncommon for child domestic workers to be fed leftovers or less or poorer quality food than the family, which can lead to malnutrition, a state that is especially harmful during child growth periods [13]. As children in circumstances of employment, who are unable to assert their rights, they may also be subjected to harsh methods of discipline (corporal punishment, shouting, deprivation of food etc.) for perceived misbehavior or poor performance [12,14,15]. There are numerous accounts from around the world of severe forms of abuse, including extreme physical violence or sexual harassment and the abuse of child domestic workers by males in the household and other males visiting the household [16]. As a result of feelings of powerlessness and low selfconfidence, children often feel unable to reject sexual advances or object to exploitation or abuse [13].
Psychological distress, trauma, and subsequent mental health problems are not uncommon among child domestic workers. Young workers often suffer from isolation and the absence of affection and age-appropriate care, alongside being marginalized in the home and experiencing discriminatory treatment by household members [9]. Young people are also generally unable to manage the feelings and emotions that result from circumstances of neglect [13]. These adverse experiences are often compounded by feelings of bereavement due to family separation and loss of affection [2]. Moreover, few working children are permitted to participate in education or access health or social services [9]. The longer-term pathways and health outcomes of child domestic workers have not been studied, but anecdotal accounts suggest that child domestic workers may transition to adult domestic work or marriage arrangements and youth workers may turn to sex work as a less restrictive, more lucrative option than domestic work [17].
While studies have repeatedly suggested the societal costs of child domestic work [18], measuring adverse childhood experiences among child domestic workers has been challenging, in part, due to the invisible nature of their circumstances and also because of the methodological limitations associated with exploring adverse childhood experiences among particularly marginalized youths [2,19,20]. Nonetheless, a growing number of quantitative studies on child domestic workers are offering prevalence estimates and documented health risks and consequences. This study aims to present evidence on the nature of adverse events (specifically violence) and health outcomes among child domestic workers to inform targeted interventions for child domestic workers. This review focuses on low-and middle-income countries (LMIC) and relevant high-income countries (HIC), including Singapore, Taiwan, Macau, Hong Kong, and Brunei, where domestic work is common [7,21]. This review is part of a program of work focusing on child domestic work in LMICs [20]. The primary objective of the review is to describe and synthesize the evidence on violence and health outcomes associated with child domestic work.

Search Strategy
We searched six electronic databases: MEDLINE, EMBASE, Global Health, Econlit, Web of Science, and the International Bibliography of the Social Sciences. We searched for studies published through July 2019, and search terms and concepts were developed by the research team. We also checked the most relevant websites for relevant grey literature: ILO Labourdoc, Freedom Fund research library, Understanding Children's Work (UCW), Anti-Slavery International, Save the Children, Population Council, UN agency, and the Young Lives website. Letters, commentaries, conference abstracts, books, and book reviews were excluded. We did not track the citations of included studies because of time constraints. The search methodology is stated in the protocol registered as number CRD42019148702 in the PROSPERO database of systematic reviews [22]. Search terms and the timeline for searches can be found in Supplementary File S1.

Inclusion and Exclusion Criteria
Studies were included if they (1) reported any type of physical, sexual, and emotional/psychological violence and/or work-related disease/injuries of child domestic workers (<18 years); (2) described a subgroup analysis or disaggregated data for child domestic workers; (3) were conducted in LMICs and selective HICs, as mentioned above; and (4) were published in English between 1990 and 2019.
As with the primary focus of the review on violence and health outcomes associated with children working as domestic helpers outside their immediate family in their childhood, studies were excluded if they (1) focused on adult domestic workers only (>18 years) and did not report disaggregated data for outcomes of interest among child domestic workers; (2) included only children or young adults (up to 25 years old) performing household chores or care work in their own homes with immediate family; or (3) featured child domestic worker profiles and health literacy or health care utilization, without reference to any of the relevant outcomes. The screening protocol can be found in Supplementary File S2.

Data Extraction and Critical Appraisal
The details of the process of data extraction used are described in another paper published by the study authors [20]. In summary, studies initially identified were uploaded to Rayyan, and duplicates were removed. Two reviewers (CC and NP) screened study titles and abstracts and selected potentially eligible studies for full-text review according to the inclusion criteria. The same reviewers cross-checked each other's lists of potentially eligible studies and randomly checked excluded studies. Two reviewers independently carried out full-text reviews. CC created the data extraction form and extracted data from 75% of the included studies, while NP did so for the rest. Disagreements were discussed and resolved during data extraction.
For this current review, AT extracted information from each study, and this included the study setting, country, study population, age, study design and measurement tool, sampling method, and summary estimates of violence and health outcomes. In this review, we focus on the prevalence of health and violence outcomes among child domestic workers.
The overall study quality was appraised using the Joanna Briggs critical appraisal tools (CAT) for the relevant study design. We also assessed the quality of the measurement tools used to capture violence and health outcomes using a measurement quality appraisal tool (QAT) developed in a previous study [23]. For the measurement QAT, we extracted data on the method of assessing the outcomes; information on the validity and reliability of measures and any translation of the survey instrument; modifications for cultural sensitivity to questions, and the method of survey administration. Checklists of both appraisal tools are provided in Pocock et al. [20]. For the overall quality appraisal, studies were scored as follows: 0-50% Poor, 51-75% Moderate, 76-100% Good (Appendix A Table A1). The measurement tool quality was rated as follows: 0-3 "poor", 4-5 "moderate", and 6-7 "good" quality. A value of 0 was assigned for studies lacking information on a particular domain [20] (Appendix A Table A2).

Data Analysis
We employed a narrative synthesis approach, since the objective of our study was to describe violence and health outcomes, not to explore associations between exposures and outcomes [24]. Different types of abuse and violence examined in the included studies were grouped into physical, emotional, and sexual violence when studies did not report individual type of violence separately. Operational definitions of types of violence and study populations are summarized in the Appendix A Tables A3 and A4. Violence prevalence was defined as the proportion of child domestic workers who experienced any form of violence (physical, sexual, emotional). When not mentioned specifically for child domestic workers, proportions of those affected were calculated from absolute numbers and relevant information given in studies [10,[25][26][27][28]. When types of abuse were reported in the study (e.g., 8.9% slapped/beaten with bare hands, 2.4% beaten with objects), the abuse type with highest percentage was used ('slapped/beaten with bare hands' was taken for physical violence) [26]. Prevalence estimates of emotional and sexual violence from 8 studies, and physical violence from 9 studies were extracted, and median values were calculated in excel, as the data were skewed. We interpreted the findings based on recent literature and the quality of study and measurement tools. A meta-analysis was not conducted due to heterogeneity in the study population, definitions, outcomes measured, and methods of assessing health and violence. The prevalence of interested outcomes was calculated from the reported absolute numbers when not specifically described for child domestic workers in the study.

Results
After the removal of duplicates, we identified 6573 records (see Figure 1). After the study titles and abstracts had been screened, 211 studies were selected for a full-text review. Finally, a total of 17 full studies based on 16 studies and articles were included in the review.
Behavior and mental problems

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Migrants had a more advanced puberty status than non-migrants: breast development according to Tanner's stage (p = 0.045) and occurrence of menarche (p = 0.014).

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After controlling for the effect of sexual maturation on nutrition and growth, migrants had a higher mid-arm circumference (p < 0.001), body mass index (p < 0.001), and fat mass index (p < 0.0001) and a lower stature (p < 0.0001) than non-migrants.
There appear to be regional differences in physical violence. In Togo, 49% of children (n = 200) reported being physically punished for mistakes, and in India, 35% (n = 500) were physically punished, while in Peru, no child domestic workers (n = 199) reported abuse, similar to the Philippines, where 58% (n = 200) said they were "just talked to" in response to mistakes [14].

Sexual Violence
The prevalence of sexual violence ranged from 0-62% among former or current child domestic workers [10,12,[26][27][28][29]32,37]. In Haiti, childhood experience as a domestic worker was considered to be a risk factor for sexual violence [OR: 1.86; 95% CI: 1.34-2.58; p = 0.0001] [37]. Findings from India indicated a large disparity in sexual violence between child domestic workers and control children compared to the difference in Togo. For example, when asked if they know someone who has been sexually abused, 25% of child domestic workers vs. 1.2% of controls in India responded "Yes", while twice as many child domestic workers as controls knew someone who had been abused in Togo [14]. In Ethiopia, nearly one-third of child domestic workers felt sexually insecure at home, which was related to experiences of sexual abuse [32].

Health Outcomes
Sixteen studies described health outcomes categorized into physical health (workplace related conditions and nutritional status), behavioral and mental health, and health care seeking.

Physical Health
In a multi-country study that deployed snowball surveys, child domestic workers selfreported having good or very good health in Tanzania (80%), Philippines (65%), Peru (51%), Togo (46%), and India (36%) [14]. In Brazil, child domestic workers had a 1.2 times higher prevalence of experiencing musculoskeletal pain compared with non-working children [adjusted prevalence rate (aPR): 1.17; 95% CI: 1.05-1.31] [35]. Children who reported working in awkward positions were [aPR:1.15; 95% CI: 1.02-1.30] times more likely to have experienced musculoskeletal pain compared with a non-exposed group [35]. A study in Ho Chi Minh city, Vietnam found that 76% of children reported that their health remained the same after working as a domestic worker, and 17% said their health was better [10].

Workplace Illness, and Injury
The percentages of child domestic workers who reported work-related illness varied: 7% (n = 115) in Thailand [25], 36% (n = 100) in Vietnam [10], 67.9% (n = 3841) in Bangladesh [28], and 63% (134/213) in Senegal [34]. Patterns of illness varied among these who fell ill. For example, over 70% of child domestic workers in India and Bangladesh reported gastro-intestinal infections and fever, respectively [27,28]. One-third of child domestic workers in Vietnam reported respiratory problems, and 25% reported back pain (25%) and cuts (11%) [10]. Work-related injury and illness were reported by 4% of child domestic workers aged 10-14 years and 7.6% aged 15 to 17 years [31]. However, injuries were more commonly reported by younger workers [10]. Findings from Cambodia indicated that among those reporting injuries (n = 293), one-quarter had been slashed by sharp objects, 10% had slipped in the bathroom, and 6.2% reported electrical shocks [26]. Feelings of exhaustion, insomnia, and fear were reported by one-fifth of youths [26].
In Brazil, child domestic workers had the lowest prevalence of workplace injury/illness compared to child laborers engaged in other forms of potentially hazardous work [31]. For example, the study findings indicate that injuries or illness were reported by 6.57% of those involved in domestic work, 8.2% of those involved in street work, 13.85% of those involved in construction, and 14.87% of those involved in hazardous farming [31]. However, results from South Africa suggest a difference in the risk of injury or illness based on paid versus unpaid work, as the proportion of paid child domestic workers who had been injured (8% of 53,942) was double that in other economic sectors (4% of 3, 243,942), such as unpaid housekeeping and family care, unpaid maintenance and cleaning, begging, farming, and collection of fuel and water [29].

Nutritional Status
Stunting seemed to affect a substantial number of child domestic workers in the South Asia studies. Among child domestic workers aged 8-14 years, 55% in India [27] and 90.4% in Pakistan [30] were stunted. Nearly one-third of those in Pakistan had severe stunting [30], and among both groups, 5.7-9.4% were affected by a thin/very thin body mass index (BMI) [27,30]. In Senegal, migrant child domestic workers tended to reside in more socio-economically affluent environments, and they had more advanced breast development (p = 0.045) and occurrence of menarche (p = 0.014) and better nutritional status: higher mid-arm circumference (p < 0.001), body mass index (BMI) (p < 0.001), and fat mass index (FMI) (p < 0.0001) compared with non-migrants in rural areas [34].

Behavioral and Mental Health
Findings from Brazil suggest that child domestic workers in low-income urban areas have a 1.6 times higher prevalence of behavioral problems [aPR: 1.6; 95% CI: 1.0-2.7; p = 0.052] than children who do not work [36]. In a multi-national study, the difference in psychosocial wellbeing between child domestic workers and controls in India and Togo was substantial while the disparity was not obvious in the Philippines, Peru, and Tanzania [14]. The proportion of child domestic workers (67%) with psychosocial scores in the lowest stratum was more than twofold that of controls (25%) (p < 0.001) in India, while in the Philippines, there was a 6% difference between the two groups (p = 0.2) [15]. Importantly, the findings suggest an influence of abuse on psychosocial well-being, as children within the lowest tercile for psychosocial well-being were more likely to have been harshly punished (beaten/deprived of food) in India [OR: 3.6; 95% CI: 3.2-4; p < 0.0001] [15]. In a study on nine provinces in South Africa, twice as many child domestic workers feared being hurt by someone (13%) compared with children working in other sectors (7%) [29]. Limitations to socializing were reported by a study in Ethiopia, with 2.5% of child domestic workers (n = 100) reporting difficulty in socializing with others compared with 0.3% of non-laborers (n = 400) (p = 0.006) [33].

Health Care Seeking
In Vietnam and Thailand, approximately half of sick or injured child domestic workers said they were not treated for their injuries [10,25]. Almost all child domestic workers who reported being ill in Bangladesh had received some form of treatment (self-treatment, doctor, pharmacy, traditional healer, treated by employers), even though one-third of them had to work during sickness [28].

Working Conditions
The average number of working hours reported by child domestic workers ranged from 9 to 15 h per day in Bangladesh, Vietnam, India, and Ethiopia [10,12,28,32,34]. Working hours were reported differently across studies, and findings showed that 95% of workers in Pakistan worked overtime (unspecified hours) [30]. High numbers of children worked between ten and twelve hours per day, including 95% in India, 65% in Tanzania, and 52% in Togo [14]. In Thailand, 78% worked more than eight hours per day [25], and in Cambodia, 10.2% said they worked between nine and thirteen hours per day [26]. In Brazil 70% of youths aged between 10 and 17 years old worked more than 30 h per week [31]. Findings from India, Thailand, Cambodia, Vietnam, and Ethiopia indicated that children had no rest days, ranging from 31% in West Bengal, India to 94% in Ho Chi Minh, Vietnam [10,12,14,25,26,32].
In addition to domestic chores, child domestic workers were involved in caring taskschild and elderly care, washing legs and feet, helping family members to bathe; outdoor chores-gardening, pet feeding, fetching water and fuel, taking children to school, going to market; and employers' businesses-helping with family businesses and garages, helping to sell commodities in open market petty trade, farming-herding cattle, milking cows, cattle raising, and paltry nursing [12,14,[25][26][27][28]30,32]. In Ethiopia, 45% of CDWs carried/lifted heavy loads beyond their capacity, while some handled hot water, hot iron, and sharp knives for chores [32]. Forty-two percent of CDWs in Brazil used machines/chemicals at work, whereas only one-third of them wore protective gear or received training [31]. A total of 14-23% of CDWs in Brazil and South Africa performed heavy physical work, monotonous/repetitive work, and or work in an awkward posture [29,35].

Critical Appraisal of Study Quality and Measurement Tools
Based on the Joanna Briggs critical appraisal tools (Appendix A Table A1), four studies were scored as "good" [33,[35][36][37], three were "moderate" [26, 28,34], and ten were "poor" [10,12,14,15,25,27,[29][30][31][32]. Studies were rated 'poor' mainly because of unclear self-reporting methods, particularly regarding sample size, data analysis, outcomes, and response rates. Likewise, elsewhere [20], overall study quality appraisal scores were different from the critical appraisal ratings of the measurement tools in the majority of studies (Appendix A Table A2). For four studies that were ranked "good" in terms of the overall study quality, their measurement tools were appraised as poor [33,37] and moderate [35,36]. No studies scored 'good' for their measurement tools. Three of the twelve violence studies and four of the fifteen health studies were rated 'moderate' for the quality of their measurement tools, while the rest scored 'poor' (Appendix A Table A2).
No studies used an internationally validated screening tool to assess child violence exposures. Most often, authors conceived their own violence questions, or questions were loosely based on the limited questions for violence available in the ILO Statistical Information and Monitoring Programme on Child Labor (SIMPOC) questionnaires, which have not been formally validated. However, three studies [33,35,36] used internationally validated tools to measure health outcomes; two were validated for use with children including the Child Behavior Checklist (CBCL) for behavioral problems [36], the Reporting Questionnaire for Children (RQC) to screen behavioral/mental problems, and the Diagnostic Interview for Children and Adolescents (DICA) to confirm diagnosis for screening positive cases [33]. The Standardized Nordic questionnaire for musculoskeletal symptoms was not originally developed for use with children; however, it has been used in child labor studies [35,38,39]. Health outcome measures, including psychosocial health, were usually developed by the researcher. Limited studies examining occupational health outcomes used questions from ILO SIMPOC model questionnaires, which have not been formally validated.
Ethical approval was not mentioned in five violence and health studies [26][27][28][29]32] or two health studies [31,36]. Only one study stated that it adhered to the WHO guidelines for ethics and safety recommended for research on violence against women [37]. A quarter of studies [14,32,33,37] noted the use of methods to ensure cultural appropriateness.

Discussion
This rapid systematic review provides a narrative synthesis of the violence, health outcomes, and working conditions of child domestic workers. Child domestic workers are generally excluded from mainstream child protection and education services and are vulnerable to different forms of violence and maltreatment in employing households [9]. Importantly, working conditions and children's experiences, including exposure to violence, and the circumstances in which children perform different tasks are critical contributing factors to the ways in which child domestic work affects children's health, development, and safety. Ultimately, we identified 17 studies conducted in low-and middle-income countries that described violence and health outcomes experienced by child domestic workers. Half of the studies were conducted in Asia, while the rest were conducted in Africa and America. Our analysis estimated that the median reported rates of violence in child domestic workers aged 5-17-year-olds are 56.2% (emotional violence), 19% (physical violence), and 2.2% (sexual violence). By region, Asia had lower median prevalence rates of physical and sexual violence compared with the Americas and Africa. It is, however, difficult to generalize regional prevalence estimates, as only one-third of the 17 studies [10,26,28,29,37] were nationally or regionally representative samples, whereas the remaining studies used convenience or purposive samples. Definitional variations in measuring abuse and violence across the studies also make comparisons difficult.
Across the studies, emotional violence had the highest prevalence (over 50%) compared with other forms of violence, and this also varied by region-over 50% in Asia and North and South America and 92% in Africa. This aligns with estimates by the World Health Organization (WHO) that psychological abuse is the most commonly reported form of maltreatment in a child's lifetime [40]. This number also echoes the findings from another global systematic review that estimated that over 50% of children (2-17 years) across the world have experienced some form of abuse in the past year [1,41]. Despite a lack of clarity on whether the reported violence occurred over the lifetime or in the past year in many of our included studies, reported prevalence rates indicated that different forms of violence were experienced in employing households. According to the WHO, restricting a child's movements is considered a form of emotional or psychological violence [42]. Only a few studies in this review documented movement control. For example, findings from Thailand and Ethiopia indicated that a large number of CDWs are restricted to their employers' premises [25,32]. Accounting for movement restriction in future research may help to estimate emotional abuse and its effects. There can be little doubt that during a child's development, the absence of caregiving, including emotional support, compounded by emotionally abusive treatment by the main adults in a child's life, will cause long-lasting damage to a child's healthy psychological growth and well-being, including feelings of self-confidence.
Verbal abuse is treated as a form of emotional violence if it is continuous and severe and negatively affects an individual's emotional state [43,44]. Perceived verbal abuse that damages brain development is associated with diverse personality and behavioral disorders and produces long-lasting consequences [43,44]. The effects of emotional violence, either acting alone or together with physical and sexual violence, may be intensified when they interact with pre-existing adverse childhood experiences, such as restricted freedoms, long-term separation, and parental loss. Our review highlights the importance of emotional violence among child domestic workers that is harmful to children but may not be considered as important as physical and sexual violence [44]. During a child's years of social development, verbal abuse such as repeated insults, criticisms or threats, is likely to have effects that last into adulthood.
Notably, the median prevalence rate of sexual violence among child domestic workers (derived from LMIC studies) was comparatively lower than the WHO's global lifetime sexual violence prevalence figures of 8% for boys and 18% for girls [40]. In our review, studies that reported sexual contact and mixed forms of sexual violence were more prevalent than those that measured non-contact and unspecified forms, including sexual harassment and abuse. The prevalence may have been affected by the type of sexual violence that was measured, as respondents might have been more likely to recall more serious episodes that involved contact versus those that seemed less harmful or without contact. This finding is similar to results from studies in Ethiopia, in which approximately one-third of young Ethiopian domestic workers below the age of 25 had experienced coerced/forced sex, suggesting that domestic work is a risk factor for non-consensual sex and early sexual initiation [45,46]. However, there remains debate about whether the form of sexual violence affects the reported prevalence [46,47]. Geographical variations and under-reporting due to shame may also affect differences in reported prevalence between studies. Given the likelihood of underreporting and the severe damage to youth who suffer sexual abuse or harassment, there can be no doubt that these types of abuse call for more sensitive forms of investigation and stronger prevention initiatives.
From our review, we cannot draw conclusions on whether violence prevalence rates among child domestic workers differ by sex, as most studies did not collect sex-disaggregated data, because females generally dominate the domestic work sector [48] and are at a higher risk of experiencing sexual violence than males [37,40,47,49]. In this review, the nationally representative Haitian household survey demonstrated that female former child domestic workers have a greater risk of experiencing physical violence, and former male child domestic workers have greater odds of experiencing emotional violence and a similar risk of experiencing sexual violence compared with females [37]. However, the survey measurement tool used in the Haitian study [37] was appraised as poor due to a lack of information on its validity and reliability. Thus, further research is required to support this finding.
The findings of this review add to the evidence that violence against children has consequences for health and wellbeing by specifying the abuse experienced by children in domestic work [50,51]. In our review, physical violence and punishment were shown to cause severe physical injuries (Ethiopia and West Bengal, India) [12,32] and can also be attributed to poor psycho-social wellbeing (India and Togo) [14] and poor self-reported health (India and the Philippines) [15]. For instance, in Ethiopia and Cambodia, the majority of child domestic workers who had experienced violence suffered from depression, fear, insecurity, suspicion, worthlessness, anger, apathy, and insomnia. [26,32]. This aligns with research from a nationally representative study from the United States where children who were physically punished or abused (with or without physical punishment), had increased odds of having two or more psychiatric disorders between the ages of 15 and 54 years old [52].
Our review highlights the critical issue of child domestic workers engaged in hazardous work and working conditions. The child domestic workers surveyed in many studies from Asia and Africa worked more than nine hours per day with no rest days, and those who worked long hours with fewer breaks had poorer psycho-social well-being and a higher incidence of injuries in India and Brazil [15,31]. Research shows that working over 60 h per week increases the risk of mental health problems and cardiovascular diseases [4,53]. The ILO recommends uninterrupted rest daily and a minimum of 24 h rest after working consecutively all week for domestic workers [54]. Although specific evidence and recommendations for children are lacking, age-specific work hours and regular rests are particularly important for children because, biologically, they need longer sleep hours and adequate rest and are prone to fatigue [4,18].
In addition, child domestic workers from studies in this review engaged in physically harmful work (e.g., carrying heavy loads, using machines and chemicals, being exposed to noise, unnatural movements) and mentally exhausting tasks (e.g., caring for children and the elderly), generally without adequate safety measures. Compared with adults, the developing bodies of children are exceptionally susceptible to occupational hazards. For instance, children's thinner skin easily absorbs high doses of toxics and heavy metals, their rapidly growing skeletons are more vulnerable to unnatural posture and movements, and their premature thermoregulation is more sensitive to temperature. All of these factors predispose them to increased risks of neurobiological problems, immune impairment, non-communicable diseases, musculoskeletal disorders, respiratory problems, and cancer [18,35,55]. In this review, a study from Brazil showed that children working in awkward positions had a higher prevalence of musculoskeletal problems [35].
This review confirms that accidents due to poor working conditions are common. Child domestic workers reported injuries from cuts [10], slashes, electrical shocks, falling from stairs, and sore fingers and toes from detergent use [26]. They may be particularly prone to accidents because of their inability to correctly assess dangers and threats [4] and due to mental and physical exhaustion resulting from overwork, occupational stressors, and violence [18]. Evidence indicates that night work, heavy work, and exposure to physical hazards increase the likelihood of workplace injury in working children by 40% [18]. Subsequently, youth workers have higher rates of occupational injury, illness, and fatality compared with adult workers [18]. Our review also found that child domestic workers suffer from malnutrition, gastrointestinal infection, anemia, stunting [27,30], vitamin deficiencies, skin disease, musculoskeletal problems [10,35], and respiratory problems [10,27]. Child domestic workers also have poor access to care and may not receive the required medical treatment or rest unless the employers permit this. Results indicate that one-third of child domestic workers that reported feeling sick in Bangladesh had to work [28], while approximately half of sick or injured child domestic workers in Thailand and Vietnam did not receive adequate treatment [10,25].
The quality of studies included in our systematic review was variable, as fewer than half of cross-sectional surveys (7/17) were assessed as having medium to good quality study design; however, the measurement tools used to assess health and violence outcomes in studies were scored as moderate to poor. No studies used an internationally validated screening tool to assess child violence outcomes. Most of the measurement tools were conceived by researchers, and study authors provided very limited information on the development of measurement tools. The study quality would have been improved if study instruments drew on validated health and violence measures in LMIC contexts, followed by pilot testing, cognitive interviews, and options for adaptation in different countries. No studies reported cognitive interviews and the majority of studies did not mention the culturally sensitive modification of questionnaires (n = 14) or pilot testing (n = 12), which are criteria for assessing measurement tools.
Research on violence against children requires particular attention to ethical, safety, cultural, and legal concerns. Questioning young people about abusive experiences may cause youths to recall traumatic experiences, which means that adequate referral mechanisms must be in place to provide the necessary support. Moreover, in many locations, there are also legal child protection reporting requirements. Furthermore, having strong protocols in place to ensure anonymity and confidentiality is essential for the safety of participants. However, seven studies reported no information on ethical or safeguarding procedures for the research, including five violence studies [26][27][28][29]32] and two health studies [31,36]. However, ethics was not applied as appraisal criteria.

Strengths and Limitations of the Study
To the best of our knowledge, this is the first systematic review to document violence and health outcomes among child domestic workers. However, this review has certain limitations. First, we extracted available heterogenous information of child abuse and violence from the studies that used different sampling strategies to calculate the median violence estimates. We used median estimates as the data were skewed, and mean estimates may not provide accurate estimates. The content and clarity of the questions used to assess violence in the studies differed. Eight studies asked CDWs about the specific types of abuse they had experienced ('have you ever been punched, kicked, whipped, or beaten with an object, choked, smothered') [37], while the remaining six reported proportions of child domestic workers who had been 'physically punished' or who had experienced 'mental assault' or 'sexual violence' without specifying the acts included under these categories [14,27]. As with many studies using self-reporting measures, for consistency and accuracy, we excluded violence rates reported through indirect questions ('know someone who has been abused') [10,14]. We also recognize that children may be scared to report honestly about abuse, especially sexual abuse, due to fear or shame. For these reasons, the median violence estimates from this review are likely to be underestimates.
Second, the impact of violence on health and well-being escalates with the degree of adverse experiences for children exposed to abuse. Exposure to one ACE doubles the risk of poor health, and experiencing more than four ACEs triples the risk of poor health compared to children with no exposure at all [51]. Furthermore, the consequences of inter-relatedabuse may cause stunting, which in turn predisposes individuals to low self-esteem and other behavioral problems [56]. Given the likelihood of multiple interacting proximal and distal factors being associated with violence and maltreatment, it is difficult to disentangle the effects of violence associated with child domestic work. For example, child domestic workers may be affected by other adverse experiences such as separation or loss of parents, chronic poverty, and domestic violence in their birth family, in addition to violence at their employing household.
Third, there is no clear consensus on the difference between physical punishment and physical abuse [57]. Physical punishment, in many contexts, is considered a normal disciplinary tool, while abuse is considered to be harmful for child health and development [57]. However, these forms can often overlap, because physical punishment as discipline may also be harsh and harmful [58]. This review shows that one-third to half of child domestic workers surveyed in Ethiopia and India (West Bengal) had experienced bodily injuries due to what was recorded as physical punishment. As it is difficult to distinguish between physical punishment and abuse in these studies, beating, hitting, and slapping were considered physical violence, even though these behaviors may be committed for correctional purposes, which would have influenced the reported rates of physical violence.
Fourth, this review did not observe any significant association between behavior and mental health problems and child domestic work, although both conditions were more common in child laborers in the two studies [33,36]. This may be because both studies were unable to adjust for the effect of violence and child abuse on mental health problems among child domestic workers [33,36]. If child domestic workers have been abused, the impact of this on health may appear in early childhood or later in adult life [36,51]. For instance, a study in New Zealand which prospectively followed up children exposed to physical and sexual abuse in childhood, found associations with the mental disorders depression, anxiety disorder, conduct disorder, substance use, and suicidal tendency, which appeared between the ages of 16 and 25 years [59]. As the studies in our review are cross-sectional studies, this kind of longitudinal causal associations could have been missed. Finally, similar to the paper by Pocock et al., we assessed the study quality and measurement tools based on the authors' reporting, and we were unable to distinguish whether poor scoring was due to incomplete reporting or poor study design or measurement tools [20].

Implications for Research and Programming
Our findings demonstrate that child domestic workers are more likely to be exposed to various forms of violence and occupational hazards compared with child workers in other sectors or non-working children. Importantly, violence exposure appears to influence whether domestic work increases the risk of adverse health outcomes in children. Despite extrapolating the idea that occupational risks are harmful for children from the data available, we cannot provide conclusive evidence on which elements of work and frequency and severity of hazardous work can threaten the health, safety, and well-being of child domestic workers. Simply asking tasks of child domestic workers is not enough, because studies need to ask specifically about what, where, how, and how long they work on each task for to determine occupational hazards. Because of the wide range of workrelated risks, e.g., harsh chemicals, sharp knives, cooking, especially for small, growing bodies, future research should explore occupational hazards relevant to child domestic work. Longitudinal studies that follow child domestic workers into adulthood may be required to determine and differentiate the effects of child domestic work and abuse on health and provide well-informed child protection strategies [60].
Our results also indicate the need for programming that is specifically designed to reach children who are involved in domestic work. Because these youths work in relative isolation, away from public view, initiatives to address emotional, physical, or sexual abuse and promote healthy child development will have to address the behaviors of employers while identifying the most effective ways to provide support to abused youths.
Community-based violence-prevalence interventions that include poverty reduction alongside psycho-social activities in areas where there is a high density of CDWs may have promise [61]. However, these strategies may also exclude youth who are the least visible and hardest to reach. Currently working youth may benefit from combined interventions that aim to change social norms around child domestic work and simultaneously provide young workers with useful skills training and viable opportunities to improve their future livelihoods.

Conclusions
In conclusion, our review highlights the associations between child domestic work, violence, particularly emotional violence, and effects on health. Our results also suggest the poor working conditions and occupational hazards that place these young workers at risk of accidents and injuries. Ultimately, our findings suggest the need for greater attention and more strategic action to protect young people in situations that are often hidden from view. Behavioral change interventions that identify and shift the harmful norms and behaviors and increase awareness about children's vulnerability to occupation hazards targeted to employing households may improve the living and working conditions of young workers through changing the social acceptance and tolerance of violence and exploitation of child domestic workers.       have been punched, kicked, whipped, or beaten with an object; choked, smothered, or experienced an attempted drowning; intentionally burned or scalded; and/or had or been threatened to have a weapon used against them.
unwanted sexual touching, attempted sex, pressured sex, and physically forced sex by any perpetrator type.
have ever had someone "say that you were not loved or did not deserve to be loved; that they wished you had never been born or were dead; ridiculed you or put you down; threatened to abandon you or threatened you that they would force you to leave home."

Zainab and Kadir 2016
Intentional use of physical force against a child. This includes slapping, hitting, beating, kicking, shaking, pushing, and pulling, biting, scalding, and burning.   (30) Children aged between 10-14 years performing domestic work at their employers' homes. 4 Gamlin 2015 (14) Children under 18 who work in the households of people other than their closest family doing domestic chores, caring for others, running errands and sometimes helping their employers run small businesses from home. 5 Hesketh 2012 (15) Children under the age of 18 who work in an employer's home performing household duties such as cooking, cleaning, child care and care of older people. 6 Banerjee 2008 (27) Children aged under 14 performing domestic chores at others' houses, caring for children, and running errands among other tasks 7 Alem 2006 (33) Children aged between 8 and 15 years engaged in paid or unpaid economic activities including domestic work, weaving, street work, commercial sex work, and work in establishments (shops, garages, hotels, carpentries, and metal workshops). Controls are child non-laborers of the same age randomly picked from the same household or from a neighboring household. Children under 18 years employed by adults other than their parents working inside the house of others for cash or in kind, regardless of whether the child attends school on a full-time or part-time basis or not. 17 Phlainoi 2002 (25) Children aged below 18 years currently working as a DW in Bangkok, current CDWs over 18 years who began domestic work before age 18, children of the same age residing at rural areas who are not working. CDWs perform household chores and/or help with the business of employers.